For some reason my replies aren’t getting posted, so here is the text of the reply to Tim’s ‘rule of thumb’ method of assigning motive power to trains.

I found an article in the November 1978 Model Railroader on tractive effort, horsepower, grades, etc. for both prototype and model railroads. The article describes a method for scaling those forces down for practical operations on a model railroad. The conclusions are similar to yours, Tim. The ruling grade on my layout is 2% in the helix. Based upon staging track capacity, mainline freight trains are limited to a maximum of 28 cars plus ABBA F units while passenger trains are limited to 14 cars plus AA E units. The A/D track in the yard can accommodate 20 cars, so trains terminating in the yard are limited to that number.

Nelson Moyer